Piter DeVries was a 'twisted mentat' -- that is, he was grown in an axlotl tank by the Tleilaxu, and purchased by Baron Harkonnen. Twisted mentats push themselves harder than normal mentats, and Piter once took so much melange he was not capable of talking for over a week. He is considered to be the exact opposite of Thufir Hawat in the books. His name is Piter DeVries in all the books he appears in, including Dune and its two prequels, House Atreides and House Harkonnen. A third prequel, House Corrino is expected out soon, or may already be out, I regretfully don't know. In my opinion, he is the third most interesting character in the entire series, next to Miles Teg and Duncan Idaho, with the God Emperor coming in a close fourth and Muad'Dib afterwards.